Method of making brake drums



June 30, 1931. G. M'. EVANS 1,811,999

METHOD OF MAKING BRAKE mum's Filed Feb. 29, 1928 IN VEN TOR. Gordon/Milling Patented June 30, 1931 UNITED TAT S]. PATENT oFI-ucs- GOBDON I EVANS, NEW YORK, N. Y., ASSIGNOR 'I'O BUDD WHEEL COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENN SYLVANIA if men. or mine BRAKE barns Ap lication "fled February as, 1928. serial near-1,815.

The present invention comprises a method of makin brake drums and other similar articles. he primary object. of the invention is the provision of a method whereby the braking surfaces of the drum are made perfectly cylindrical, all taper and out of .roundness being eliminated The invention is therefore adaptable not only to the manufacture of brake drums, but also to any other 0 use wherein similar results are desired.

Other objects, and the advantages of the invention will become apparent from the subjoined specification and claim. The attached drawings form a part of said speci- 5 fication and comprise:

Figure 1., an inside plan view of a roughlyformed drum, as drawn from the flat blank; Figs. 2 and 3, successive sectional views of the drum before and during the contracting or shrinking operation;

Fig. 4, a similar sectional view of the drum after machining, and

Fig. 5, a fra mentary-sectionalview of the drum attache to a hub.

When brake drums, or other articles similar to the drum 10 shown in the drawings are drawn or pressed from flat blanksor sheets of metal (usually steel), the flange '12 of said drum is flared, or coned, as shown in Figures 1 and 2, the said flange 12 extending from the a right angle. This is due to the combined .efl'ect'of the resilience of the metal and the provision of clearance between the. punch and lower die of the forming dies. Since both of these factors are inherent 'in' the metal and due to the method offorming, the above condition has been accepted heretofore and" remedied-by machining off the excess metal 'to obtain perfectly cylindrical inside and outside surfaces on the flange 12. Because of the machining operation, a thicker blank is needed than the circumstances require, in order to provide the proper thickness of flange in the finished article.

The present invention eliminates the loss of both time and material due to the above usage and produces a more uniform and economical structure. The blank is drawn,'or

web 11 of the drum at some angle other than signature.

the fiange 12, in the conical'or flared shape.

Instead of machining this flange to a cylinder, however, the drum is next placed in thedies 13 0f a contracting or shrinking machine,- similar to that shown in-the patent to Grotnes, numbered 1,407,148, dated Feb.

21, 1922, in which a circularlyarranged group 9 of such dies are shown having mechanism to move'them forcibly inward toward a common center u on a ring, then contracting or h ki t t d d d s rin ng e ring 0 any es1re egree.

'Having placed the drum in the dies of the above n echine (herein represented by the dies 13) the said machine is set in motlon in the direction of the arrows 14, Figs. 2 and In this way, the flange 12 is reduced to a true cylinder. There remains only the operation of grinding, or lightly machining the working surfaces of the drum (as in Figure 4) to produce a finished product. The last step serves to give an even surface, free from small defects, for the brake shoes tooperate upon. The lines 1 .1 common to Figures 2, 3 and 4 indicate, in .an'exaggerated way, the changes made by each operation.

The effect of the shrinking operation ma readily be confined solely to the flange, ma ing it possible to treat malformed drums which (as shown in Figure 5) have already been mounted on a hub 15. By contracting such mounted drums and taking a light machinin or 'inding cut over the working faces t ereo the original or desired concentricityand cylindrical shape may be restored or obtained.

' lVhat I claim is The method of making a brake drum or period of exertion of said inward pressure.

. In testimony whereof I hereunto aflix my GORDON M. EVANS;

cupped, just as in the prior method, leaving 

